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Slow speeds on fibre with pppoe

Posted: Fri Jan 25, 2019 7:10 pm
by cushenst
Hi,
A few of us are trying to figure out why we aren’t getting full speed through a fibre connection. The fibre link has been tested to be capable of 1gbps.

We have a pppoe Server running on a vlan on a ccr1016-12S-1S+ which then connects through the fibre on a vlan to a rb1100ahx2. This runs a pppoe client on the vlan.

Then highest speed we are able to achieve is about 500-520mbps when running a btest from client to server. We have been told the line mtu is 1500. The negotiated mtu of the pppoe interface is 1480.

Only a basic configuration is on both routers. Any advice would be great. If you require any more information please let me know.

Stephen

Re: Slow speeds on fibre with pppoe

Posted: Fri Jan 25, 2019 7:24 pm
by jprietove
Test mtu with ping and no fragment option. VLAN has additional bytes in header so instead of 1480 maybe it's 4 bytes less.


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Re: Slow speeds on fibre with pppoe

Posted: Fri Jan 25, 2019 7:56 pm
by cushenst
Thanks for your reply. I am able to ping both ways with a max packet size of 1480 without it complaining of fragmentation. (1480 all pings fine. 1481 pings fail due to fragmentation).

Re: Slow speeds on fibre with pppoe

Posted: Fri Jan 25, 2019 9:17 pm
by Paternot
Then highest speed we are able to achieve is about 500-520mbps when running a btest from client to server. We have been told the line mtu is 1500. The negotiated mtu of the pppoe interface is 1480.
Are You running the btest client/server on the routers being tested? One shouldn't do it, as the btest is quite CPU hungry, and will affect your speeds.

Try running something between two computers, behind the routers.

Re: Slow speeds on fibre with pppoe  [SOLVED]

Posted: Tue Feb 05, 2019 8:50 pm
by cushenst
Hi, Thanks. We were able to lower the mtu to 1436 and that seems to have solved the problems. We are now maxing out our transit providers.